The invention generally relates to a gas lift valve.
A well typically includes a production tubing string for purposes of communicating well fluid to a surface of the well through a central passageway of the string. Due to its weight, the column of well fluid that is present in the production tubing string may suppress the rate at which the well fluid is produced from the formation. More specifically, the column of well fluid inside the production tubing string exerts a hydrostatic pressure that increases with well depth. Near a particular producing formation, the hydrostatic pressure may be significant enough to substantially impede the rate at which the well fluid is produced.
For purposes of reducing the hydrostatic pressure and thus, enhancing the rate at which fluid is produced, an artificial-lift technique may be employed. One such technique involves at various downhole points in the well, injecting gas into the central passageway of the production tubing string to lift the well fluid in the string. The injected gas, which is lighter than the well fluid displaces some amount of well fluid in the string. The displacement of the well fluid with the lighter gas reduces the hydrostatic pressure inside the production tubing string and allows the reservoir fluid to enter the wellbore at a higher flow rate. The gas to be injected into the production tubing string typically is conveyed downhole via the annulus (the annular space surrounding the string) and enters the string through one or more gas lift valves.